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PubMed2006

Ribosomal protein l19 is a prognostic marker for human prostate cancer.

Microquantity differential display analysis of gene expression profiles between benign (PNT2) and malignant (PC3M) human prostate cell lines identified the gene encoding ribosomal protein L19 (RPL19) to be overexpressed in the malignant cells. Northern blot hybridization analysis done on a wide range of human cell lines and tissues confirmed the level of RPL19 mRNA to be 5-fold higher in malignant cell lines and 8-fold higher in malignant tissues, when compared with their benign counterparts. Analysis of RPL19 mRNA expression by in situ hybridization revealed a significant increase of RPL19 expression in a substantial number of prostate cancers. All of the eight normal prostatic tissues were unstained (100%). Of 32 benign prostatic hyperplasia (BPH) tissues, 15 (46.9%) were unstained, 9 (28.1%) stained weakly, and 8 (25%) stained moderately. Among 87 carcinomas, only 7 (8.1%) were unstained, whereas 22 (25.2%) stained weakly, 21 (24.1%) stained moderately, and 37 (42.61%) stained strongly. The intensity of staining of the malignant specimens was significantly higher than that of normal and BPH specimens (chi(2): n = 127, P < 0.001). Gleason scores of the carcinomas correlated with RPL19 expression (chi(2): n = 87, P < 0.001). Kaplan-Meier survival analysis confirmed increased RPL19 expression to be highly predictive of shorter patient survival (P < 0.05), revealing RPL19 to be a sensitive predictor of prostate cancer progression. Expression of this protein could be a valuable marker in prostate cancer diagnosis and patient management.

Biomarkers, Tumor↗

PubMed1998

Small angle neutron scattering analysis of thermal stability of 23S rRNA and the intact 50S subunits of Sulfolobus solfataricus.

The ribosomes of the extremely thermophilic archaebacterium, Sulfolobus solfataricus, are very resistant to thermal denaturation (optimal growth temperature 87 degrees C), remaining essentially intact up to above 90 degrees C. However, the separate ribosomal components (rRNA and r-proteins) are less thermally stable than the ribosome as a whole, indicating that the mode of interaction of all of the components within the ribonucleoprotein particle play an essential role in determining thermal stability. To get some insight into the structural features of the thermophilic ribosome, we performed small angle neutron scattering (SANS) measurements at various temperatures on Sulfolobus solfataricus intact large ribosomal subunits (50S) and deproteinated large ribosomal subunit RNA (23S). Even if the scattering profiles suggest the presence of supramolecular aggregates in all of the samples and at all of the investigated temperatures, the measured form factors indicated for both samples that, at temperatures above 70 degrees C, the suspended particles underwent a structural rearrangement. This finding is likely to reflect single particles' properties, since S. solfataricus ribosomes are known to be biologically activated only above 60 degrees C, and there are indications that such activation requires a conformational rearrangement of the particle. A remarkable superimposition of the percentage variation of the volume from neutron scattering and of the absorbency increment with respect to temperature supports this view.

Neutrons↗

PubMed1976

Synaptogenesis in the ventromedial hypothalamus of the prenatal mouse.

Mouse embryos from day 13 to day 19 of gestation (E13 through E19) were removed by Caesarean section and their brains were prepared for electron microscopy. Coronal sections were examined in three planes through the ventromedial hypothalamus: anterior, the level at which the optic tracts pass posterolaterally to become partially enclosed in the major brain mass; middle, the level at which the floor of the third ventricle begins to widen and flatten; posterior, the level at which the most anterior infundibulum appears. Three types of junctional complexes were examined. Close junctions are identified as straight, parallel areas of two apposed membranes which appear more electron-dense than immediately adjacent regions. The membranes are separated by a clearly visible cleft. Unlike synapses, no clear synaptic vesicles are found in either of the adjacent profiles unless randomly distributed and accompanied by ribosomes or glycogen. Close junctions are seen most frequently on day E15, then decrease in number through E19. Their participation in synaptogenesis is discussed from temporal, morphological, distributional and quantitative perspectives and is provisionally rejected. Immature synapses show only the minimal membrane specialization found in close junctions, but vesicles are present, ribosomes absent in at least one of the adjacent cytoplasms. Their appearance peaks on E17-E18, paralleling and slightly preceding that of the mature synapses. Their evolution from close junctions has only weak temporal support. Mature synapses display the cytoplasmic densities which immature synapses lack. They attain their greatest prenatal numbers on E18, then decrease in number on E19. The conclusion is advanced that synaptogenesis does--or at least can--occur without the prior appearance of avesicular regions of increased membrane density.

Animals↗

PubMed1988

Occurrence of 40 S.polysomal complexes in polysome profiles of reticulocyte lysates.

In most reticulocyte lysates 40 S.polysomal complexes have such a short lifetime that they will not show up in the polysome profile. Here we describe a reticulocyte lysate where these 40 S.polysomal complexes apparently have a highly increased lifetime and therefore these complexes can be seen in the polysome profile as shoulders on the di-, tri- and tetrasome peak. The presence of these complexes in lysates probably signals an increased speed in the association of 40 S subunits with mRNA since similar alterations as described above show up in the polysome profile of normal lysates to which native ribosomal 40 S subunits were added.

Animals↗

PubMed1987

Effects of intraneural injection of Ricinus communis agglutinin-60 into rat vagus nerve.

The dorsal motor nucleus (DMN) of the rat was studied at various survival periods following an intraneural injection of Ricinus communis agglutinin-60 (RCA-60) into the vagus nerve at the mid-cervical region. No obvious structural changes were noted in the DMN 2 and 4 days after the injection of RCA-60. At 5 and 6 days after the RCA-60 injection, the larger neurons (measuring 19 X 12 microns) in the DMN underwent chromatolytic degeneration whereas the smaller ones (measuring 10 X 6 microns), characterized by their infolded nuclei, remained unaffected. The majority of the degenerating DMN neurons became pale and crenated in outline. Other structural changes included swollen mitochondria with disrupted cristae and profiles of rough endoplasmic reticulum denuded of ribosome particles. A few of the degenerating neurons became extremely condensed and darkened. Axon terminals which showed synaptic contacts with these cells remained normal. Both pale and darkened degenerating dendrites, derived from the degenerating neurons, were present in the neuropil. In addition to these, degenerating axon terminals with clumping or swelling of synaptic vesicles were also present. They were presynaptic to dendrites of various sizes. Massive infiltration of mononuclear cells occurred in the DMN. These cells reached the DMN by diapedesis and were actively engaged in the phagocytosis of degenerating neuronal elements. While most of the invading cells transformed into active neuronal macrophages, some of them eventually died in the neuropil of the DMN. Light microscopic study by Fink-Heimer's method for degenerating fibres and terminals revealed their distribution to the DMN, nucleus of the tractus solitarius, nucleus commissuralis, dorsolateral and lateral part of the hypoglossal nucleus and the area postrema. It was concluded from this study that RCA-60, when injected into the cervical vagus was retrogradely transported to the cell body of the DMN neurons of the larger category. The selective destruction of the DMN neurons by RCA-60 elicited a massive infiltration of mononuclear cells which gave rise to the neural macrophages. The RCA-60 injected also killed the vagal sensory neurons as demonstrated by the numerous degenerating fibres and axon terminals in the DMN which would represent their central processes.

Animals↗

PubMed2000

Ultrastructure of the normal adult human female prostate gland (Skene's gland).

The predominant cells of female prostatic glands lining their lumen were found to be tall cylindrical secretory cells with short stubby microvilli, protuberances of the apical cytoplasm, and with bleb formation. Abundant secretory vacuoles and granules, rough endoplasmic reticulum, developed Golgi complexes and numerous mitochondria are characteristic of their active secretory configuration with apocrine (apical blebs) and merocrine (secretory vacuoles and granules) type of secretion. Basal (reserve) cells were seen to be located between the secretory (luminal) cells and the basement membrane. Their ground cytoplasm is dense with rough endoplasmic reticulum and mitochondria. Their nuclei, unlike those of secretory cells, possess more peripheral condensed chromatin, denser dispersed chromatin and sporadic nucleoli. Besides the two basic types of mature prostatic cells intermediary cells were also seen, located between the basal and secretory cells or in their close vicinity. Their cytoplasm exhibits numerous profiles of rough endoplasmic reticulum and free ribosomes. Secretory vacuoles and granules were mostly practically absent (type 1 intermediary cells) so that they resembled basal (reserve) cells. In some of them, however, as in secretory cells, such secretory elements do gradually appear (type 2 intermediary cells). The finding of intermediary cells in the lining of prostatic glands supports the role of basal (reserve) cells in the renewal of cells in glands of the female prostate. The first ultrastructural analysis of the normal female prostate performed by transmission electron microscopy showed that, as in the postpubertal male, the prostatic glands in the adult female display mature secretory and basal cells. The results of the presented study further corroborate the contemporary concept of the female prostate as a functional genitourinary organ.

Adult↗

PubMed1989

An ultrastructural study of human epithelial rests of Malassez maintained in a differentiated state in vitro.

Healthy human periodontal ligaments (PDL), obtained from the extracted teeth (premolars and third molars), were cultivated for 1-35 days, using a multi-purposes culture chamber (MPCC) equipped with various transparent membranes. The resting state of the epithelial rests of Malassez (ERM), similar to their in vivo counterparts, appeared as small islands or strands with scant cytoplasm containing poorly developed organelles. This state was most effectively maintained in MPCC with a cellophane sheet. MPCC with a Sartorius membrane filter permitted proliferation and emigration of ERM. Proliferating ERM were characterized by more profiles of rough endoplasmic reticulum and free ribosomes, new formation of actin-containing microfilaments, less prominent tonofilaments and desmosomes and loss of gap junctions. Most of these ultrastructural changes are manifested in epithelial cells during wound healing. The emigrating ERM from PDL explants, as well as occasional proliferating ERM within explants, consisted of two cell types--outer basal-like cells, as described above, and inner tonofilament-rich prickle-like cells, suggesting a propensity for differentiation of ERM. The results show the possibility of controlling the growth and differentiation of ERM through the MPCC culture environment.

Adolescent↗

PubMedDate not supplied

Medical technologists using molecular epidemiology as part of the infection control team.

Two medical technologists were appointed as permanent members of a new epidemiology section in the diagnostic microbiology laboratory of a large Veterans Administration Medical Center in the fall of 1989. These positions accounted for 9% of the total microbiology staff and were created on a temporary basis 2 years earlier from a need to have dedicated technical expertise for use in the culture, isolation, and typing of nosocomial organisms. The technologists have evaluated outbreaks due to Clostridium difficile, methicillin-susceptible Staphylococcus aureus, and Serratia marcescens, and have begun work on a methicillin-resistant Staphylococcus aureus (MRSA)-typing scheme. Their major responsibility has been the development and application of molecular biology techniques for the typing of nosocomial isolates, including restriction enzyme analysis of genomic DNA, plasmid profiling with and without restriction enzyme analysis, ribosomal RNA probing of restricted genomic DNA, and selected DNA sequencing of target organisms. Medical supervision rests jointly between the directors of the infection control program and the microbiology laboratory. During their tenure, infections due to C. difficile have dropped from 95 cases per year to 57 cases annually, treatment of MRSA colonization with systemic agents has been curtailed, and a case control investigation involving S. marcescens was avoided. The inclusion of medical technologists in the infection control practice of large medical care facilities, particularly with the availability of molecular epidemiologic techniques and the emergence of increasing numbers of multiply-drug-resistant pathogens, will become an essential component of these programs.

Bacterial Infections↗

PubMed2026

Proteomic responses of the oil palm pest Metisa plana (Psychidae) to farnesyl acetate exposure.

Metisa plana Walker (Lepidoptera: Psychidae) is a major defoliator of oil palm in Malaysia, causing substantial economic losses. Farnesyl acetate (FA), a sesquiterpenoid compound, has been proposed as a potential insecticidal agent against M. plana, yet its molecular impact on larval physiology remains poorly understood. Here, we employed label-free quantitative proteomics, functional enrichment analysis, and targeted transcript assessment to characterize the temporal proteomic response of M. plana larvae at 7 and 14 days after treatment (DAT) with FA. Principal component analysis revealed robust separation between treated and control samples at both time points, indicating sustained treatment-driven proteomic restructuring. Early exposure (7 DAT) elicited a heterogeneous response involving stress-associated proteins, redox enzymes, and cytoskeletal regulators, whereas later exposure (14 DAT) produced a consolidated profile characterized by metabolic reprogramming, downregulation of ribosomal proteins, induction of heat shock proteins, and enrichment of RNA surveillance and mitochondrial pathways. Targeted transcript analysis qualitatively supported proteomic trends for HSP83 and aldehyde dehydrogenase X, although limited amplification precluded quantitative inference. Collectively, these findings demonstrate that FA exposure drives a shift from acute proteomic perturbation toward a maintenance-oriented physiological state, prioritizing proteostasis, energy management, and stress adaptation over growth and development. This integrated molecular perspective provides mechanistic insight into the chronic effects of FA, highlighting its potential to suppress larval performance and informing the development of biorational, physiology-based pest management strategies in non-model insects.

Animals↗

PubMedDate not supplied

Tamoxifen induces ultrastructural alterations in membranes of Bacillus Stearothermophilus.

Tamoxifen (TAM), a non-steroid antiestrogen, is the mostly used drug for chemotherapy and chemoprevention of breast cancer. However, the mechanisms by which TAM inhibits cell proliferation in breast cancer are not fully understood. TAM strongly incorporates in biomembranes and a variety of effects have been assigned to biophysical and biochemical interactions with membranes. Therefore, a better understanding of the physicochemical basis of interaction of TAM with biomembranes is essential to elucidate the molecular mechanisms of action. A strain of Bacillus stearothermophilus has been used as a model to clarify the interaction of TAM with the cell membrane. TAM effects on the ultrastructure of membranes of this bacterium were evaluated by electron microscopy. Important ultrastructural alterations were observed in B. stearothermophilus treated with TAM, namely change in the geometry of the membrane profile from asymmetric to symmetric, disaggregation of ribosomes, coagulation of the cytoplasmic matrix, occurrence of mesossomes, appearance of fractures in membranes and the alteration of the ultrastructure of cell wall. These ultrastructural alterations confirm that TAM is a membrane-active drug and that membrane damage may be involved in molecular mechanisms of cell death induced by this drug.

Dose-Response Relationship, Drug↗

PubMed1971

Changes in macromolecular synthesis associated with the induction of glutamine synthetase in embryonic retina.

The hydrocortisone-mediated induction of glutamine synthetase in the neural retina of chicken embryo in vitro is correlated with enhanced incorporation into protein of [(14)C]aspartic acid, an amino acid abundant in this enzyme. In the induced retina labeled with [(14)C]aspartic acid, a peak of radioactivity was detected in the region of the polysomal profile corresponding to polysomes comprising 12-14 ribosomes. In retinas labeled with [(3)H]uridine, an increased amount of radioactivity was also detected in the same polysomal region of the hydrocortisone-induced retina. If we assume a monocistronic messenger RNA for retinal glutamine synthetase, this region corresponds to the estimated size of the polysomes necessary for the translation of this enzyme. The evidence presented demonstrates a correlation between these changes in incorporation and the induction of glutamine synthetase.

Animals↗

PubMed2002

Culture-independent microbial community analysis reveals that inulin in the diet primarily affects previously unknown bacteria in the mouse cecum.

Inulin is a well-known fructose-based prebiotic which has been shown to stimulate the growth of bifidobacteria, a bacterial group generally considered beneficial for intestinal health. In the present study, we analyzed inulin-associated shifts in the total bacterial community of wild-type mice and mice carrying a genetically inactivated adenomatous polyposis coli tumor suppressor gene by using DNA-based approaches independent of bacterial culturability. Mice were fed a high-fat, nonfiber diet with or without inulin inclusion at a 10% (wt/wt) concentration. Cecal contents were analyzed after 0, 3, and 9 weeks on the experimental diets. Inulin inclusion significantly affected the total bacterial community structure of the cecum as determined by both a nonselective percent-guanine-plus-cytosine-based profiling analysis and a more specific 16S ribosomal DNA sequence analysis. The shifts included stimulation of bifidobacteria and suppression of clostridia, but sequence comparison revealed that the major shifts were within previously unknown bacterial taxa. Concomitantly, significantly higher bacterial densities, determined by flow cytometry, were observed with the inulin-amended diet, and the metabolism of the cecal bacterial community was altered, as indicated by higher levels of residual short-chain fatty acids, particularly lactic acid. With regard to all of the microbiological parameters measured, the wild-type mice and mice carrying a genetically inactivated adenomatous polyposis coli tumor suppressor gene were essentially identical. Studies of the implications of pre- and probiotics may need to be expanded to include careful analysis of their effects on the entire microbial community, rather than just a few well-known species. Further studies are needed to increase our understanding of the possible roles of currently unknown gastrointestinal bacteria in health and disease.

Animal Feed↗

PubMed1993

Suppression of protein synthesis in the reperfused brain.

BACKGROUND: Brain ischemia and reperfusion produce profound protein synthesis alterations, the extent and persistence of which are dependent on the nature of the ischemia, the brain region, the cell layer within a region, and the particular proteins studied. After transient ischemia, most brain regions recover their protein synthesis capability; however, recovery in the selectively vulnerable areas is poor. It is unknown whether this phenomenon itself provokes or is a consequence of the process of neuronal death. SUMMARY OF REVIEW: Protein synthesis suppression during ischemia is due to energy depletion, but this is quickly reversed upon recirculation. Reperfusion does not appear to damage DNA or transcription mechanisms, although there are changes in the profile of transcripts being made. Similarly, purified ribosomes isolated from reperfused brains can make the normal repertoire of proteins and heat-shock proteins. However, during early reperfusion, newly synthesized messenger RNAs appear to accumulate in the nucleus; this alteration in RNA handling could reflect disruption at any of several steps, including posttranscriptional processing, nuclear pore transport, cytoskeletal binding, or formation of the translation initiation complex. Another mechanism that may be responsible for protein synthesis suppression during late reperfusion is progressive membrane destruction, with consequent shifts in the concentration of ions crucial for ribosomal function. CONCLUSIONS: Protein synthesis suppression after ischemia likely involves a progression of multiple mechanisms during reperfusion. Although the recent work reviewed here offers new insight into the potential mechanisms disrupting protein synthesis, detailed understanding will require further investigation.

Animals↗

PubMed1997

Phylogenetic position and geographic differentiation of the Japanese dormouse, Glirulus japonicus, revealed by variations among rDNA, mtDNA and the Sry gene.

The Japanese dormouse, Glirulus Japonicus, is the only extant lineage that represents this genus and it has been classified as a single species distributed on the three main islands of Japan, namely Honshu, Shikoku and Kyushu. However, individuals collected from Fukui, Wakayama and Kochi Prefectures (southwestern part of Japan) yielded distinctly different profiles of restriction fragments of the nuclear ribosomal DNA (rDNA) spacer from those collected from Yamanashi and Nagano Prefectures (central Japan). The estimated sequence divergence between the two groups was 2.8% on average, which corresponds to a putative divergence some two million years ago. Representing mitochondrial DNA (mtDNA) sequences, 402 bases of cytochrome b gene were determined by direct sequencing and the estimated extent of the sequence divergence between the two groups was 6.5-7%. Differences between the two geographic groups were also substantial in the sequences of about 300 base-fragments from the Y-linked, sex-determining locus, Sry. To assess the phylogenetic relationships between the Japanese dormouse and members of the family Myoxidae, we compared sequences of mitochondrial 12S rRNA gene of Japanese dormice with those of the forest dormouse (Dryomys nitedula) and the common dormouse (Muscardinus avellanarins), two continental genera thought to be closely related to the genus Glirulus. The results showed that the sequences from Japanese dormice were distinct from any sequences of the two continental species and the extent of the differences were somewhat similar to that between the rat (Rattus norvegicus) and the hamster (mesocricetus auratus).

Animals↗

PubMed1999

Hybridization among sympatric species of Rhododendron (Ericaceae) in Turkey: morphological and molecular evidence.

Rhododendron (Ericaceae) is a large genus in which barriers to hybridization are especially weak, but many species are maintained in sympatry. Hybridization among four species of Rhododendron subsect. Pontica, which occur in sympatry in Turkey, was investigated. Material of R. ponticum, R. smirnovii, R. ungernii, and R. caucasicum and their putative hybrids was collected from the wild. Based on morphology, chloroplast DNA and nuclear ribosomal DNA restriction fragment length polymorphism (RFLP) profiles, each accession was identified as a species or hybrid combination. Five of the six possible hybrid combinations among the four species were detected. Rhododendron ponticum × R. smirnovii was represented by a single individual and R. caucasicum × R. smirnovii by one small group of hybrid plants. The combinations R. ponticum × R. ungernii and R. ungernii × R. smirnovii showed evidence of frequent backcrossing, while R. ponticum × R. caucasicum appeared unusual in that an intermediate hybrid type was abundant, whereas hybrids with phenotypes approaching either parent were rare. Possible explanations of this latter situation are discussed. The results suggest that natural hybridization among Rhododendron species is common and that ecological factors are important in maintaining integrity when species occur in sympatry.

Journal Article↗

PubMed1991

The early development of the neopallial wall and area choroidea in fetal rats. A light and electron microscopic study.

The telencephalic wall was studied by light and electron microscopy in 11-13 day old fetal rats (E11-13). A few specimens from E14-16 were also included for comparisons. Two areas were selected: the dorso-lateral convexity of the hemispheric vesicles, called the neopallial wall, and the area choroidea, the posterior part of the telencephalic roof which unites the two hemispheres. Our observations and a review of the literature have shown that on E11-12 the neopallial wall, the telencephalic roof, and the hippocampal anlage between them form a continuous, nonstratified, cohesive monolayer of columnar and mitotic cells, which essentially is similar to epithelial monolayers elsewhere in the body. This simple structure is modified late on E12 or early in E13 in the neopallial wall when postmitotic neurons appear and migrate in order to form the cortical plate. However, bipolar radially oriented cells, which span the entire width of the wall, still predominate. These cells, now called radial glial cells, increase greatly in number and length during the period of neuronal migration. The cuboidal cells in the neural tube, the columnar cells in the early neopallial wall, and the radial glial cells in the period of neuronal migration have the same basic structure. They are axially polarized epithelial cells which are characterized by the following basic features. They have an elongated bipolar shape which is maintained by a cytoskeleton of longitudinally oriented microtubules. Opposite ends are different structurally and functionally. Thus, the apical ends, connected by tight junctions, face the fluid-filled cavity while the outer ends, covered by a basal lamina, face mesenchymal tissue including blood vessels. A polarization of cytoplasmic organelles is also evident, e.g. the Golgi apparatus has always a supranuclear position. During the early development of the telencephalon this basic epithelial structure is maintained but is modified locally in order to serve various functions. The columnar/radial glial cells in the neopallial wall are elongated and slender, have a narrow Golgi apparatus, profiles of RER and vesicles, relatively few ribosomes, and show a few examples of micropinocytosis. These cells grow continuously in length during development. On the other hand, the cells in the area choroidea have a low columnar or cuboidal shape, which does not change during development. The inner portion (between the nucleus and the ventricle) contains a voluminous Golgi apparatus, many mitochondria, RER cisternae which contain electron-dense material, SER, and many vesicles. The inner ends of the cells project into the ventricular cavity as bulbous or apical protrusions which contain many organelles, especially MVBs.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1980

[Fine structure of pineal gland in some Chiroptera. (Vesperugo savi and Rinolophus f.e.). I. Histochemical and ultrastructural study (author's transl)].

Fine structure of pineal gland was studied in some Chiroptera and compared with those of other micromammals. Three cells types were found in pineal parenchyma: pinealocytes, the most numerous cells, glial cells and Mastzellen. Some nervous cells were found in peripheral dorsal pineal gland. Pinealocytes show a clear or dark matrix which are different functional stages of the same cell. A large nucleus with irregular profiles and deep invaginations, several mitochondria and ribosomes, canalicular rough surfaced endoplasmic reticulum, large Golgi apparatus, lipid droplets, secretory and heterogeneous granules distinguish this cellular type. Centrioles often joined with a striated root (formed by alternating clear and dark discs), cytoplasmic process extending in the intercellular space as far as 3-4 mu including cilia showing a 9+0 pattern, osmiophilic vacuoles involved in secretion processes were observed too. Glial cells irregularly arranged tend to form small clusters: they show a dense and glycogen particles rich matrix. This matrix was very positive for non specific esterases reaction. Blood vessels are provided by a continuous endothelium resting on basal lamina, surrounded by a thick perivascular layer. Collagen fibers, pinealocytes processes, non-myelinated nerve fibers and Mastzellen were found in pervascular area.

Animals↗

PubMed1985

Morphogenesis and fate of the residual body in human spermiogenesis.

In the human testis the formation of the residual body of the spermatid and its morphological changes during and after spermiation were studied by means of electron microscopy. The caudal cytoplasmic mass of the late spermatid contains a Golgi complex, mitochondria, annulate lamellae, a chromatoid body, flower-like structures, ribosomes, a few large vacuoles, myelin-like membrane profiles and sporadic lipid droplets. When, by detachment of the caudal cytoplasm from the free spermatozoon, the residual body is formed, the chromatoid body has disappeared; the mitochondria are clustered peripherally; the ribosomes appear as a single complex in contact with a large vacuole containing granular material; in place of the Golgi complex aggregations of vesicles are present. The lipid droplets remain unchanged. The residual bodies or their fragments are either extruded via the seminiferous tubular lumen into the excurrent ducts or they are engulfed by Sertoli cells where in the supranuclear region the successive steps of decomposition can be observed. The participation of the various constituents in the disintegration of the residual body is discussed. In contrast to other mammalian species, in man the sporadic lipid droplets seem to be of minor importance in the fate of the residual body.

Adult↗