Biomedical subjects

M T Walker

Publications and source records attributed to M T Walker.

21 records · Page 2Linked to original sources

PubMed1983

Plasma concentrations of progesterone, oestradiol-17 beta and 13,14-dihydro-15-oxo-prostaglandin F2 alpha in the pregnant wallaby (Macropus rufogriseus rufogriseus).

The concentrations of progesterone and oestradiol-17 beta in the maternal plasma of Bennett's wallaby, Macropus rufogriseus rufogriseus, were measured daily throughout gestation after reactivation of the diapausing corpus luteum by removal of the suckling pouch young (RPY). Progesterone increased from mean concentrations of 382-424 pmol/l (120-133 pg/ml) during lactation to reach peak concentrations of 908 +/- 172 (S.E.M.) pmol/l (285 +/- 54 pg/ml) (n = 8) 4 days after RPY and 971 +/- 220 and 971 +/- 229 pmol/l (305 +/- 69 and 305 +/- 72 pg/ml) (n = 7) 24 and 25 days after RPY respectively. The mean gestation length (RPY to birth) was 26.8 +/- 0.6 (S.D.) days (n = 6, range 25.75-27.50 days). Immediately after birth the plasma progesterone concentration declined to 299 +/- 51 (S.E.M.) pmol/l (94 +/- 16 pg/ml) (n = 6). Oestradiol-17 beta increased from mean concentrations of 291-553 pmol/l (80-152 pg/ml) during lactation to reach a peak concentration of 967 +/- 331 pmol/l (266 +/- 91 pg/ml) (n = 9) 1 day after RPY. The concentration declined from 7 days after RPY and fluctuated between mean concentrations of 273 and 480 pmol/l before reaching a minimum of 207 +/- 69 pmol/l (57 +/- 19 pg/ml) (n = 6) 19 days after RPY. A transient increase to 542 +/- 207 pmol/l (n = 7) occurred at 22 days after RPY. Plasma concentrations declined to a low of 156 +/- 55 pmol/l (43 +/- 15 pg/ml) (n = 6) 5 days after parturition. The mean concentration of plasma 13,14-dihydro-15-oxo-prostaglandin F2 alpha was less than 2.8 nmol/l (1 ng/ml) for all samples from 13 days after RPY until 4 days after parturition. The results suggest that oestradiol-17 beta may be important in the early stages of blastocyst reactivation to synergize with progesterone in stimulating uterine secretions. 13,14-Dihydro-15-oxo-prostaglandin F2 alpha is unlikely to be involved in the birth process and any luteolytic effect is likely to be from a local production of PGF2 alpha.

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PubMed1981

Ultrastructural changes after diapause in the uterine glands, corpus luteum and blastocyst of the red-necked wallaby, Macropus rufogriseus banksianus.

Pouch young were removed from animals (Day 0) captured in the wild in order to reactivate diapausing blastocysts. The blastocyst and tissues from the uterine endometrium and the corpus luteum were preserved for electron microscopy at Days 0, 2.5, 4, 5, 6, 9, 14 and 21. At Day 0 the diapausing blastocyst is a unilaminar sphere with a diameter of about 260 micrometers. Blastocysts up to and including Day 6 did not exhibit expansion and no mitotic metaphase stages were found. Mitotic activity was present in the blastocyst at Day 9 and the overall diameter had expanded to 675 micometers. At days 2.5, 4, 5 and 6 the height of the uterine gland epithelium had increased by about 15% with a slight increase in the amount of membrane-bound secretory vesicles in non-ciliated cells of the uterine glands. The presence in these cells of numerous polyribosomes and heightened Golgi activity as well as an expansion of the endoplasmic reticulum foreshadowed the onset of a secretory phase. Electron-dense membrane-bound granules which were a most conspicuous feature of the cytoplasm of fully active luteal cells started to appear as early as Day 4. At the ultrastructural level, signs of reactivation of the blastocyst are later than those that are evident in the luteal cells and in the non-ciliated secretory cells of the uterine glands.

Animals↗

PubMedDate not supplied

Intradural primary chondroblastic osteosarcoma: case report.

We report a rare case of intradural primary osteosarcoma (IPOS) in a 74-year-old man with aphasia and right-sided hemiparesis. Radiologic workup revealed a large, partially calcified, left-sided frontotemporal intracranial mass lesion. At surgery, the tumor was found to be entirely intradural; it involved the brain and subarachnoid space of the left sylvian fissure. The adjacent dura was uninvolved. Neuropathologic findings confirmed the diagnosis of chondroblastic osteosarcoma. To our knowledge, this is the sixth reported case of IPOS and the first reported case of the chondroblastic subtype.

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