Ovarian hypoplasia in heifers due to germ cell weakness.
Ovarian hypoplasia due to germ cell weakness was found in 18 heifers of the Swedish Red and White breed simultaneously with a sharp increase of the same syndrome in bulls of the same breed. The heifers were examined because they had not shown estrus or had not become pregnant after several months on pasture together with a fertile bull. After palpation of the ovaries per rectum they were classified as normal, partially hypoplastic or totally hypoplastic. The heifers were slaughtered and the numbers of primordial follicles were counted in the serially sectioned ovaries. The average numbers of follicles per ovary in the 3 diagnostic groups were 18716, 6617 and 4761, respectively. The numbers of primordial follicles in hypoplastic ovaries were significantly lower than in normal ovaries but were still within normal limits for heifers. However, the hypoplastic ovaries were very small, and the totally hypoplastic ones weighed only 1 g or less. The growth of the primordial follicles was disturbed and very few developed into Graafian follicles. There were also many empty cortical cords and anovular follicles. The heifers had all been sired by bulls belonging to breeding lines where germ cell weakness had occurred.
Ovarian development in athymic nude mice I. The size and composition of the follicle population
Mice homozygous for the Mendelian recessive mutation nude show a reduction in the size and changes in the composition of the ovarian follicle population. Follicular loss was first evident at 2 months of age and was specifically due to a reduction in the numbers of small (primordial) follicles and medium follicles in the initial growth stages. The first ovulation was delayed until 2 1/2 months of age. By 4 months an overall reduction in all fractions of the follicle population had occurred and ovulation had ceased. These developmental changes are discussed in relation to the role of the thymus gland in sexual maturation and reproductive function in the female mouse.
Quantitative macroscopic and histological study of testicular hypoplasia in Bos indicus strain bulls.
Forty-six bulls between 17 and 23 months old were used in an investigation of testicular hypoplasia in Bos indicus strain bulls. Testes diagnosed as either unilaterally or bilaterally hypoplastic or normal were obtained at castration and were examined macroscopically and by quantitative histological methods. Estimations of sperm per gram of testis (spg) were made on these 46 bulls and two others. Testis weight was greatest in the 'normal of unilateral' group (106 g). The mean epididymis:testis weight ratio was 0.12 and did not differ significantly between groups. Increased basement membrane thickness, increased vacuolation and giant cells were not features of testicular hypoplasia per se. Seminiferous tubule diameter varied from 118 micrometer in bilaterally hypoplastic testes to 171 micrometer in normal testes. A mean tubule diameter of about 150 micrometer was considered useful for differentiating hypoplastic from normal testes in young post-puberal B indicus crossbred bulls. There was a significant correlation between tubular diameter and spg (r = 0.68, P less than 0.001) suggesting that tubular diameter measurements in histological sections could be used to predict sperm production. Although there was good agreement between clinical diagnosis and spg values, high spg values were found in several small testes which were considered hypoplastic on clinical examination. Examination of both unilaterally and bilaterally hypoplastic testes showed an interesting variation in the ratio of nucleus to cytoplasm in the interstitial cells. This was significantly (p less than 0.05) lower in the testes of normal bulls than in the other clinical groups.