Differentiation and development of the reproductive system in the iguanid lizard, Sceloporus undulatus.

Embryos of the lizard Sceloporus undulatus were sampled throughout incubation, and the differentiation and development of the reproductive system was documented histologically. The undifferentiated gonads possess both a cortex and medulla, both of which contain germ cells until embryonic stage 34. Beginning at stage 34, the cortex of the presumptive ovary thickens, and cortical germ cells are more abundant. By the time of hatching, the ovarian cortex is 6 to 10 cells thick and filled with oogonia and oocytes; primordial follicles, however, are not yet present. In males at embryonic stage 34, seminiferous tubules appear in the medulla of the testis, and Sertoli cells begin to differentiate. Seminiferous tubule formation is complete by hatching, and both Sertoli and Leydig cells are apparent. The mullerian ducts develop in both sexes but begin regressing in the male at embryonic stage 37. The wolffian ducts also develop in both sexes and are present in males and females at hatching.

Isolation of rat Leydig cells by density gradient centrifugation.

A rapid method for preparing Leydig cells from rat testes is described. An interstitial cell suspension, prepared by collagenase treatment of decapsulated testes, was centrifugal for 10 min over a cushion of 60% (v/v) Percoll to remove red blood cells, and then centrifuged for 20 min in a 0-60% linear density gradient of Percoll. Seventy-four per cent of the cells present in that fraction of the gradient comprising 35-50% Percoll were Leydig cells; the yield from each testis was about 1.5 x 10(6) cells. The Leydig cells appeared viable, excluded Trypan blue, possessed high-affinity binding sites for human chorionic gonadotrophin (hCG) and synthesized increased quantities of testosterone in response to hCG. The cells could be stored overnight in 20% (v/v) glycerol at -20 degrees C, with only minimal effect on the specific activities of a number of enzymes used as markers of subcellular components. Testosterone production in vitro by the cells after storage for 20 h was greater than that of hCG-stimulated fresh cells and was not further increased by hCG.

The effects of selective withdrawal of FSH or LH on spermatogenesis in the immature rat.

PIP: The effects of antisera specific to rat follicle stimulating hormone (FSH) and sheep luteinizing hormone (LH) on spermatogenesis were studied in 20-day-old rats. The antisera to rat FSH binds only with iodine-125 FSH, while the sheep anti-LH serum cross-reacts with rat LH. Anti-LH serum, administered over a 14-day period, caused an 80% reduction in testes weight, and a considerable reduction in the weights of the epididymides, ventral prostate, and seminal vesicles. A reduction in the size of the Leydig cells, of the diameter of the seminiferous tubules, and in the number of germ cells was observed. Serum testosterone levels were dramatically reduced (113 + or -6 pg/ml compared with 616 + or -138 pg/ml in controls). Anti-FSH serum treatment decreased testes weight by about 50% but did not markedly reduce accessory organ weights or serum testosterone levels. Although the Leydig cells appeared normal, the tubule diameter and the number of spermatocytes and spermatids were reduced below control values. It appears that anti-FSH serum inhibits spermatogenesis in the immature rat, without affecting serum testosterone levels.^ieng