A HISTOLOGICAL STUDY OF THE TESTIS IN CASES OF PSEUDO-INTERSEXUALITY AND CRYPTORCHISM WITH SPECIAL REFERENCE TO THE INTERSTITIAL CELLS

¹ The Animal Breeding Research Department, University of Edinburgh

1. A histological study was made of the testes of two intersexual pigs, and the inguinal cryptorchids of a rabbit, five two-years old horses, and a cat.

2. (a) Enormous hyperplasia and (especially in Pig II) considerable hypertrophy of the interstitial cells are seen in the case of the pigs, whilst the seminiferous tubules are small, and lined by a single layer of cells undergoing fatty degeneration.

(b) In the testis of the rabbit the tubules are lined by germ and Sertoli cells, many of the former being in mitosis. Spermatocytes in various stages of synapsis are found and many of the tubules contain spherical colloid bodies. Leydig cells are present in large quantities and are undergoing hypertrophy, the various stages of which can be followed.

(c) The tubules of the ectopic testes of the horse are somewhat reduced in size and contain spermatogonia, Sertoli cells and spermatocytes. The interstitial cells show marked hyperplasia.

(d) The inguinal testis of the cat is a normal immature organ. Some of the tubules show early stages of degeneration and contain small colloid bodies. Secondary spermatogonia are conspicuous but there are no spermatocytes. The interstitial tissue is normal and shows no hyperplasia.

3. To account for the variation in the quantity of the interstitial cells in the above cases, it is assumed that they have a dual rôle and are both trophic and endocrine.

4. Evidence of a trophic function is as follows :

(a) Fat globules and lipoids are common in the Leydig cells.

(b) In the development of the testis there is an alternation of growth between the tubules and the interstitial tissue, suggesting that the latter act as a food-reserve for the former.

(c) In work on the testis of hibernating animals hyperplasia and hypertrophy of the interstitial cells are found to occur in spring and fat-globules appear in the cytoplasm — again indicating that the Leydig cells store up food-material on which the germ-cells can draw during spermatogenesis.

5. To maintain physiological equilibrium in the testis, there must be a balance between food-material passed in by the blood-stream and food material consumed by the germ cells.

6. In cryptorchism this balance is upset owing to degeneration of the seminal epithelium and the interstitial cells absorb food of which they can no longer dispose.

7. Hyperplasia of the interstitial cells takes place in order to equalize intake and consumption and so restore physiological equilibrium.

8. The extent of this hyperplasia depends on two main factors :

(a) The metabolic condition of the individual. In the pig with its low energy output and strong tendency to store food material in the tissue, hyperplasia is immense. In inactive individuals such as the pig and tame rabbit, the cells finally undergo hypertrophy owing to accumulation of food material in the cytoplasm. This is followed by secretory inactivity resulting in intersexual secondary sexual characters (Pig I). In a very active animal the food reserve in the body will be heavily taxed and nutritive material destined for an organ which no longer functions will tend to be reabsorbed and utilised elsewhere. The Leydig cells will thus receive little more than is requisite for their own wants, hyperplasia will be correspondingly slight and thus endocrine activity will be unimpaired.

(b) The degree of degeneration of the seminal epithelium. In the pig, there is complete degeneration and enormous hyperplasia, while in the cat there is slight degeneration and no hyperplasia.

9. Data are insufficient to throw any light on the problem of pseudo-intersexuality.