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Biomedical subjects

A F Holstein

Publications and source records attributed to A F Holstein.

At least 91 records · Page 5Linked to original sources
PubMed1976

Ultrastructural observations on the differentiation of spermatids in man.

Ultrastructural aspects of the normal development of human spermatids are presented. Eight typical pictures of differentiation of spermatids are described based on cytological details of the acrosome, nucleus and tail. The transient appearance of a spindle-shaped body, connected to the principal piece of the tail, is pointed out. In most cases, malformed spermatids have developmental disturbances of only one component of the cell, e.g. of the acrosome, nucleus or tail. Some typical malformations are described.

Acrosome↗
PubMed1976

On the morphology of the human Sertoli cells under normal conditions and in patients with impaired fertility.

Sertoli cells in testicular biopsies from 7 patients with Sertoli-cell only syndrome, 8 patients who had been treated with cyclophosphamide for testicular neoplasia, 8 patients with oligozoospermia, 7 patients with cryptorchidism, and 8 patients with seminoma were examined under the electron microscope and compared with Sertoli cells of normal tissues. The investigations reveal that each of these conditions of impaired fertility is characterized of a special type of Sertoli cell. The cell pattern is either restricted to one or two of the normally occurring cell types, or modified cells predominate that might be typical of the underlying disturbances of spermatogenesis. It is suggested that the cell type which prevails in the Sertoli-cell only syndrome is capable of maintaining a basic production of a substance that inhibits FSH secretion.

Adult↗
PubMed1975

[Morphological studies on abnormal human spermatids and spermatozoa (author's transl)].

Malformed spermatids and spermatozoa in the testes, epididymes, and ejaculates of 29 apparently healthy men and in 171 patients suffering from different andrological diseases were investigated with the electron microscope. The following types of malformations are described: 1) Malformations of the acrosome in contact with the nucleus of the spermatid: Vesicular inclusions in the acrosome vesicle, asymmetric thickenings of the acrosome cap, enfolding of the acrosomal lamina into the spermatid's nucleus, partial separation of the acrosome from the nucleus, apical knob-like thickenings of the acrosome. 2) Malformations of the acrosome independent from the spermatid's nucleus: the acrosomal material is contained in small vesicles, large vacuoles, in ring-like structures, in globular or shell-like laminar structures. The nucleus of such spermatids lacks an acrosome. 3) Malformations of the nucleus: inclusions of vesicles or membranes, excessive packages of membranes, gigantic nuclear vacuoles, lack of condensation of the caryoplasm. 4) Multinucleate spermatids: two or more nuclei within the pericaryon of one spermatid are joined by an acrosome. 5) Duplicate acrosome anlagen. 6) Malformations of the tail: disorganization of the axonema, a lack or excessive numbers of tubules and fibres, doublets of the axial filaments, destruction of the neck region, a lack of the mitochondrial sheath, and enlargement of the fibrous sheath. Malformed germ cells were observed to occur in varying amounts both in apparently healthy men and in those who were apparently infertile. This indicates that germ cell malformations are no absolute indicator of male infertility. However, certain distinct types of malformations (such as round-headed spermatozoa) are definitely associated with infertility, but only if all spermatozoa in the ejaculate of a patient have the same defect.

Acrosome↗
PubMed1975

Morphology of the "spindle-shaped body" in the developing tail of human spermatids.

At the beginning of the late cap phase of the normal differentiation of human spermatids, a unique structure, the "spindle shaped body", occupies part of the future middle-piece. This spindle-shaped body was followed throughout its development, and its functional relationahip to the formation of the fibrous sheath is discussed. The spindle-shaped body disappears when the fibrous sheath is completed and the annulus moves down, giving rise to the middle-piece.

Adult↗
PubMed1975

Morphological appraisal of gametogenesis. Spermatogenetic process in mammals with particular reference to man.

The process of spermatogenesis in man can be subdivided into prenatal, postnatal and adult phases. Special attention is devoted to the cytomorphology of the germ cells in these phases, with a more detailed description of the proliferation, maturation and differentiation of the germ cells in the adult. Thus, spermatogonial renewal, meiotic division and the morphological transformations of the spermatids into mature spermatozoa are described. An outline of the structures characteristic of the latter is also given. The histological organization of the seminiferous epithelium is considered, whereby the concepts of the cycle, stage of the cycle and wave of the seminiferous epithelium are discussed. The duration of both the cycle and that of spermatogenesis of the adult are considered. The present review on mammalian, and chiefly human spermatogenic processes aims at: surveying of current concepts, and compiling of the more important facts and problems of spermatogenesis. The nomenclature and definitions advanced here arise from the concept of continuity of the processes of spermatogenesis from embryo to adult.

Adolescent↗
PubMed1975

[Light and electron microscopy studies on malformed spermatids in 2 cases of teratozoospermia].

Two distinct types of spermatid malformation resulting in teratozoospermia are demonstrated in two patients by means of light and electron microscopy. In one case of male infertility, a disturbance of the process of nuclear condensation was found which yielded pathological spermatozoa with triangular or hookshaped heads. In another case of infertility, exclusively polynucleated spermatids were detected. Atypical acrosomes, showing widely varying structural features, interconnect the nuclei. The significant of these malformations for the understanding of the differentiation of spermatids is discussed.

Biopsy↗