[Histogenesis of the immune system of the "nude" mouse. III. Postnatal development of lymph nodes and spleen: a light microscopical study (author's transl)].
UNLABELLED
In neonatally thymectomized mice, the intermediate cortical zones of the lymph nodes as well as the central portions of the spleen follicles (=thymus dependent areas, TDA) are depleted of lymphocytes within a few weeks (Parrott et al., 1966). The TDA's in the lymphatic tissues of mice homozygous for the gene "nude" (nu/nu) contain also a very small number of lymphocytes. Since only a few developmental stages of the lymphatic tissues in nude mice have been studied, an investigation of the postnatal differentiation of their lymph nodes and spleen seemed worthwhile.


MATERIALS AND METHODS
The mice (BALB/c) were maintained under specific pathogen-free (spf) conditions. Heterozygous (nu/ plus) females were mated with homozygous (nu/nu) males in order to obtain the homo- and heterozygous offsprings used in this study. Two nu/nu and two nu/ plus female mice were sacrificed at the following postnatal stages: day 1, 7, 14, 21, 35, 42, 49, 63 and 84, respectively. Newborn and 7 day old mice were fixed in toto in Bouin's solution and embedded in paraffin. From the other animals, spleen and mesenteric lymph nodes were removed and processed in an identical manner. Serial sections were cut at 5 mum and stained with hematoxylin and eosin.


RESULTS
The mesenteric lymph nodes of the nu/ plus mice studied were indistinguishable from those of other mouse strains. In the nu/nu mouse, outer cortex and medulla of the mesenteric lymph nodes were found to develop as in normal (nu/ plus) animals, while the intermediate and deep cortex underwent characteristic changes...