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MARY F. HAY

Summary.

Thalidomide, phthaloyl-dl-isoglutamine and dl-0-carboxybenzoyl-glutamic acid were administered orally to rabbits at different stages of pregnancy, at such a dose level that general maternal health, ovulation and fertilization did not appear to be affected.

When treatment with thalidomide was restricted to the pre-implantation period almost all the blastocysts were affected morphologically, particularly in the embryonic disks, but the majority developed into viable young, some of which, however, showed minor skeletal abnormalities. In one doe treated from Days 3 to 6 there was incomplete twinning. Continuation of thalidomide treatment over the time of implantation (Days 3 to 8, 9 or 10) or into later stages of pregnancy (Days 3 to 16 or 8 to 16) did not affect the number of embryos implanting, but the proportion going to term was reduced and about 40% of them were malformed. The majority of the malformations were associated with skeletal development and although some severe defects such as spina bifida and exencephaly were recorded, many of them were of a minor character and probably would not have affected the viability of the animal.

Phthaloyl-isoglutamine and carboxybenzoyl-glutamic acid were fed during the pre-implantation period only, and neither had any consistent morphological effect on the blastocysts. Litters allowed to go to term after treatment with the former were also unaffected.

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MARY F. HAY and R. M. MOOR

Agricultural Research Council Unit of Reproductive Physiology and Biochemistry, University of Cambridge

INTRODUCTION

The Graafian follicle population in sheep can be divided into two groups on the basis of the capacity that individual follicles have for secreting oestrogen when isolated from the remainder of the ovary (Moor, 1973). The most developed one or two non-atretic follicles from each animal generally produce large amounts of oestrogen in culture and can thus be classified as steroidogenically 'activated' The other follicles usually produce very little oestrogen in culture and are accordingly classified as 'non-activated'

In this paper the above classification will be used and the two groups of follicles will be considered separately. In the first section of the paper the response of the non-activated follicles to gonadotrophic stimuli will be described and related to growth and atresia within this population. The steroidogenic potential of the activated follicles at different stages of the

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MARY F. HAY and HELEN WENDLER DEANE

Summary.

An attempt has been made to study the distribution of Δ5-3β-hydroxysteroid dehydrogenase, 17β-hydroxysteroid dehydrogenase and diaphorase activities in the testes of mature stallions, boars, rams and bulls and immature piglets and calves.

Using the standard histochemical medium, Δ5-3β-hydroxysteroid dehydrogenase activity was found only in the Leydig cells of the horse, and in a few interstitial cells of some rams. A false positive reaction ('nothing dehydrogenase') was obtained in porcine testes, and no modification of the method could eliminate this. Lowering of the concentration of co-enzyme in the medium was necessary to bring out selective staining of the interstitial tissue in bovine testes.

17β-Hydroxysteroid dehydrogenase activity could not be demonstrated in the testes of any of the species examined when testosterone was used as a substrate.

Enzymes that oxidize the reduced co-enzymes, nadh 2 and nadph 2 (diaphorases), were demonstrable in testes of all four species in both the seminiferous tubules and interstitial cells.

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MARY F. HAY and R. M. MOOR

Summary.

The localization of Δ5-3β-hydroxysteroid dehydrogenase (3β-HSD) has been examined in ovarian follicles in vivo and in vitro, and related to oestrogen and progesterone production.

In vivo, during the oestrous cycle, enzyme activity was restricted to the theca interna of the one or two most advanced follicles in each animal, but was present only between Days 2 and 5 and between Day 13 and ovulation. High levels of oestrogen were found in the ovarian venous blood only when follicles containing 3β-HSD were present. When sheep were injected with PMSG, the theca interna in a number of small follicles acquired 3β-HSD activity and began to secrete oestrogen within 12 hr of the injection. The enzyme was not detected in the membrana granulosa of any follicles before ovulation but within a few hours of ovulation, 3β-HSD activity was present in the granulosa lutein cells.

In vitro, large activated follicles exhibited 3β-HSD activity in the theca interna and secreted high levels of oestrogen into the culture medium. When LH was added to the medium, oestrogen secretion was inhibited; within 48 hr, the follicles were secreting high levels of progesterone, and 3β-HSD activity was present in both the membrana granulosa and the theca interna. Dibutyryl cyclic adenosine monophosphate mimicked the effect of LH in suppressing oestrogen secretion, but did not induce production of progesterone; the distribution of 3β-HSD activity in follicles treated with this nucleotide was the same as in those cultured in control medium.

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R. M. MOOR, MARY F. HAY and R. F. SEAMARK

Agricultural Research Council Unit of Reproductive Physiology and Biochemistry, 307 Huntingdon Road, Cambridge CB3 0JQ and Department of Obstetrics and Gynaecology, University of Adelaide, Adelaide, South Australia 5000

INTRODUCTION

Important changes occur in the follicle that is destined to ovulate and also in the surrounding ovarian tissue of sheep during the 72 hr preceding ovulation. It is our purpose to describe the morphological and functional changes that take place in large follicles during the preovulatory period and to relate these to the local ovarian environment and general endocrine status prevailing at this time. A consideration of changes in the structure, blood supply and function of the ovaries in vivo, is followed by a discussion of the functional capacity of the individual ovarian components when isolated and studied in vitro. Against this background, the nature and sequence of events that occur in the preovulatory follicle and the mechanisms which regulate them

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D. G. Cran, R. M. Moor and Mary F. Hay

Summary. The structure and distribution of organelles within oocytes of developing antral follicles were studied qualitatively and quantitatively. In the smallest category of follicle (0·2–0·4 mm diam.) the Golgi was present in a peripheral position, the endoplasmic reticulum was distended and mitochondria were intimately associated with it. Processes from surrounding cumulus cells were in contact with the oolemma which was thrown up into slender villi, increasing the oocyte surface area 5-fold. In these and all subsequent follicles the oocyte cytoplasm contained numerous 30 nm particles or vesicles. As the follicles grew to about 2·0 mm the mitochondria became located in a peripheral band, interior to which were numerous large vesicles, and the villi became shorter and thicker. In follicles >2·0 mm the mitochondrial band was largely dispersed and cortical granules rested close to the oolemma. Little structural change was then observed until late oestrus. In oocytes from preovulatory follicles at this stage an internal dense zone was formed in the zona pellucida. Most of the cumulus cell processes degenerated and most mitochondria assumed a hooded appearance.

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W. D. BOOTH, MARY F. HAY and H. M. DOTT

A biochemical sexual dimorphism exists in the submaxillary gland of the pig. Patterson (1968) identified 5α-androst-16-en-3α-ol and 5α-androst-16-en-3-one in the submaxillary gland of boars but found none in the female pig. Booth (1972) isolated testosterone and 5α-dihydrotestosterone from the submaxillary glands of boars only. These observations suggest that the submaxillary gland of the boar, like that of the male mouse (Berkman & Kronman, 1970), may be a target organ for androgen. In the mouse, hypertrophy of the granular serous tubules in the submaxillary gland is known to occur under the influence of androgen (Berkman & Kronman, 1970) and the possibility that a similar situation might exist in the pig was therefore examined. In addition, the activity of Δ5-3 β-hydroxysteroid dehydrogenase in the gland was studied histochemically.

Submaxillary glands were removed from nineteen Large White X Essex pigs of different ages, and weighed within 30 min of slaughter (see

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J. D. O'Shea, Mary F. Hay and D. G. Cran

Summary. Sixteen antral follicles, 1·8–4·2 mm in diameter, at various stages of atresia, were studied by electron microscopy. Deletion of theca interna cells by condensation followed by fragmentation (apoptosis), with subsequent engulfment of the fragments by remaining thecal cells, was present at all stages, but was most marked during secondary and tertiary atresia. In primary and secondary atresia, the relative numbers of thecal cells whose cytoplasm was rich in tubular endoplasmic reticulum were higher than in non-atretic follicles of comparable size. During tertiary atresia the number of cell layers in the theca interna was reduced, and cells rich in tubular endoplasmic reticulum became proportionately less numerous. Degenerating cellular material was present within the lumina of thecal capillaries at all stages of atresia. Such material was rarely seen in primary atresia, and increased in incidence progressively in later stages. It was concluded that during atresia a large number of theca interna cells are deleted by apoptosis, and many thecal capillaries become blocked with cellular debris.

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C. LUTWAK-MANN, MARY F. HAY and D. A. T. NEW

Summary.

The action of various agents was investigated on 6-day-old rabbit blastocysts in vivo and in vitro. The blastocysts were examined by the flat-mount technique. The substances studied included antimetabolites (2-deoxyglucose, 2-deoxyglucose-6-phosphate, 2-deoxygalactose, 6-mercaptopurine and 6-mercaptopurine riboside, ethionine, isoniazid, analogues of vitamin B12), enzyme inhibitors (dl-glyceraldehyde, salicylate, bromoacetylcarnitine, p-chloromercuribenzoate, fluoride), antimitotic agents (colcemid, aminopterin), cytostatic agents (actinomycin D, cytochalasin B), metabolites (DNA, glucose-6-phosphate, 2-deoxyribose, galactose), and hormones (polyoestriol phosphate, growth hormone). The influence of anoxia was also investigated, with special reference to temperature.

Agents which, under the experimental conditions laid down in this study, exerted clearly recognizable effects in vivo and in vitro, were 2-deoxyglucose, 6-mercaptopurine riboside, colcemid, isoniazid, aminopterin and DNA. Agents that were found to act in vitro only, were 2-deoxygalactose, glyceraldehyde, salicylate, bromoacetylcarnitine, 2-deoxyglucose-6-phosphate, actinomycin D, cytochalasin B, p-chloromercuribenzoate, and anoxia. An agent inert in vitro, but conducive (with longer exposure) to embryonic death in vivo, was polyoestriol phosphate. Growth hormone too, was inactive in vitro, but produced a slight effect in vivo. No effect was demonstrable in rabbit blastocysts following treatment with ethionine, analogues of vitamin B12, fluoride, glucose-6-phosphate, 2-deoxyribose, galactose.

Blastocysts, obtained from rabbits that had been subjected to embryotoxic agents (2-deoxyglucose, colcemid), were capable of recovery and further growth in vitro when the damage incurred in vivo was of a minor to moderate degree. Blastocysts moderately damaged by maternal 6-mercaptopurine or 6-mercaptopurine riboside treatment did not recover significantly; however, blastocysts more severely affected by these two compounds in vivo deteriorated further after incubation in vitro. Pretreatment of rabbits with polyoestriol phosphate yielded blastocysts which developed subsequently in vitro particularly well.

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R. V. SHORT, T. MANN and MARY F. HAY

Summary.

Results are presented of detailed dissections of the reproductive tracts of eight adult male African elephants and of one full-term male foetus, together with additional information obtained from the examination of a number of other bulls and cows.

A notable feature of the elephant's tract is the absence of a pampini-form plexus, cremaster muscle and inguinal canal; this is consistent with the intra-abdominal location of the testes. The weight of the testes and the mean diameter of the seminiferous tubules appear to be related to the size and hence the age of the animal. Active spermatogenesis was observed in all the adult testes examined. Testosterone was isolated from the testes and identified by infra-red spectroscopy ; the testicular testosterone concentrations ranged from 3 to 490 μg/100 g testis and were apparently unrelated to season, age, behavioural status or vesicular fructose concentrations.

The elephant has no anatomically distinct epididymis. The wolffian duct is highly convoluted and probably several hundred metres in length. Its caudal half has an unusual histological appearance, with a very folded and extremely vascular lamina propria. The ampullae are large glandular structures, opening into the ducts of the corresponding seminal vesicles. The seminal vesicles are large, thick-walled sacs that contain up to 350 ml of a watery secretion rich in fructose. The prostate varies in shape considerably between animals, being uni- or multilobular. The bulbo-urethral glands are large, and full of a highly viscous secretion.

The penis has a well-developed corpus cavernosum penis and large paired levator penis muscles on its dorsal surface.

The temporal gland is apocrine in nature, with a strongly smelling serous secretion. Its secretory activity appears to be unrelated to the reproductive status of the animal or the body temperature. The mean deep body temperature was found to be 36·8° C (range 36·2 to 37·5° C).

Spermatozoa, recovered within 2 to 6 hours of death from the caudal end of the wolffian duct and the ampullae, were immotile, but could be partially activated by dilution with vesicular secretion. At least two of the elephants had had a retrograde ejaculation when they were shot, and in one instance motile spermatozoa were recovered from the bladder 6 hr after death.