REGULARITIES AND IRREGULARITIES IN THE STRUCTURE OF THE SEMINIFEROUS EPITHELIUM IN THE DOMESTIC-FOWL (GALLUS-DOMESTICUS) .2. COORDINATION BETWEEN GERM-CELL ASSOCIATIONS

It was investigated in the domestic fowl, whether a mechanism for a sy nchronous stan of the proliferation of the differentiating spermatogon ia in a transversely cut seminiferous tubule (called the ''co-ordinati on' between germ cell association) operates effectively in this specie s. A trapezoid-shaped cellular association demarcated by two perpendic ulars from the tubular lumen to the basement membrane was the unit of observation (provisionally called a ''column'' Each column is composed of a bundle of elongate spermatids and the neighbouring, various type s of germ cells). The extent of closeness of the co-ordination was exa mined in a total of 2,650 columns, based on the continuity of the sper miogenic sptep-number of the youngest generation of spermatids within adjacent columns. In no case did all columns in a tubular cross sectio n show the same-step spermatids. In most cases (50.2 % of 2,650 column s), the same number was kept in only 2 to 6 adjacent columns. The arra ngement of different but consecutive numbers (e. g., 1-2-3 or 1-2-1) w as observed in a total of 882 columns. The co-ordination mechanism, th erefore, is considered to work, albeit incomplete, among a limited num ber of adjacent columns in this species.