Pituitary and cerebellum of nude mice.

The anterior pituitary of athymic homozygous "nude" (nu nu) mice shows signs of reduced activity of the acidophilic cells, nuclear volumes of which lag significantly behind normal values. Also there is a significant deficiency in the number of basophilic cells. A similar deficiency is found in the numbers of Purkinje cells of the cerebellum, which in addition also show a reduction in size, as part of an overall reduction of cerebellum size.

Interferon production in athymic nude mice.

Athymic (homozygous nude) mice of a non-inbred stock had relatively little antiviral activity in their serum compared with normal control mice at 4, 6 and 6.5 h after the intraperitoneal injection of Newcastle disease virus. The antiviral activity in the serum had the characteristics of interferon. At 10 h after injection and thereafter, the serum titres were comparable in nude and normal control mice. Exceptional nude mice with thymus-like tissue sometimes produced interferon more or less normally. Transfer of spleen cells from normal donor mice, but not from nude donors, led to increased serum interferon levels in nude recipient mice at 4 h after virus injection.

Ovarian development in athymic nude mice V. The effects of PMSG upon the numbers and growth of follicles in the early juvenile ovary.

The composition and growth patterns of the ovarian follicle population have been determined in early juvenile athymic nude mice and their phenotypically normal littermates. Nude ovaries contained significantly more primordial follicles and fewer trilaminar follicles at 10 days of age. The rate of growth of the oocyte nucleolus was significantly less than in control ovaries. Treatment with PMSG from days 7 to 9 restored the rate of oocyte nucleolar growth in nudes to control levels. PMSG also increased the number of follicles commencing growth in both nudes and controls and the differences in the numbers of primordial and trilaminar follicles were no longer detectable. The data demonstrate that abnormalities in the ovarian follicle population of the nude are detectable as early as the 10th day of life and can be reversed by treatment with exogenous gonadotrophin. These results are discussed in relation to the role of the thymus gland in ovarian development and the competence of the early juvenile ovary to respond to gonadotrophin.

Ovarian development in athymic nude mice. IV. The effect of PMSG and oestradiol on the growth of the oocyte and follicle.

Retarded follicular and oocyte nucleolar growth rates in ovaries of 1 month old congenitally athymic nude mice are restored by pregnant mare serum gonadotrophin (PMSG). By contrast oestradiol-17beta depresses follicular growth rate in phenotypically normal (control) mice to levels found in nude littermates. Paradoxically, oestradiol-17beta stimulates nucleolar growth rate in control mice, but not nudes, to levels found in PMSG treated groups. These results are discussed in relation to the position of the thymus gland in the pituitary/ovarian axis and the mode of action gonadotrophin upon oocyte and follicular growth in the pre-puberal mouse ovary.

Ovarian development in athymic nude mice. III. The effect of PMSG and oestradiol upon the size and composition of the ovarian follicle population.

The response of 1 month old congenitally athymic nude mice and their phenotypically normal littermates to exogenous pregnant mare serum gonadotrophin (PMSG) and oestradiol-17beta has been tested. An equal increase in the number of growing follicles was detected in both nudes and controls in response to PMSG. A specific increase occurred in the number of unilaminar follicles in the initial growth stages in addition to the increase in the number of multilaminar and vesicular follicles. Oestradiol depressed follicular growth equally in both nudes and controls. The contracted appearance of growing follicles in nudes disappeared under the influence of PMSG and was induced in ovaries of control mice treated with oestradiol. We conclude that the ability of the mouse ovary to respond to exogenous PMSG and the oestradiol is not impaired by congenital athymia as expressed in the nude genotype. The data suggest that the retardation of follicular growth already reported in 1 month old nudes arises from a deficiency of gonadotrophin.

Ovarian development in athymic nude mice. 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.

Ovarian development in athymic nude mice. II. The growth of the oocyte and follicle.

Congenitally athymic mice homozygous for the Mendelian recessive mutation "nude" develop well defined morphological and quantitative changes in the ovarian follicle population. A decline in follicle numbers at 2 months of age is preceded by a retardation in follicle growth at 1 month of age. The growth of the oocyte and its nucleus are not affected by the nude mutation. However, the rate of growth and maximum size of the oocyte nucleolus are reduced in nudes. These developmental events are discussed in relation to the genetic activity of the oocyte, the role of pituitary gonadotrophins in follicular and oocyte growth and the possible role of the thymus gland in these processes.