抄録
The chromosomes of goat and sheep were investigated from the comparative standpoint in male germ cells. The observations were carried out on the testicular material derived from two breeds in the goat and three breeds in the sheep. So far as the scope of the present study is concerned, there was found, either in the goat or in the sheep, no visible and appreciable difference in the chromosomes among the breeds under consideration, not only in the number but also in the other external morphological features of chromosomes.
The number of chromosomes in goat was found to be 60 in diploid and 30 in haploid. All the chromosomes are comprised in the rod-shaped elements of simple telomitic type, and they are placed in the paired arrangement into 29 homologous pairs of autosomes which form a closely graded seriation, and an unequal pair of the X and Y chromosomes. The X chromosome is quite prominent in being the largest of all and displays distinguishable characteristics. The Y element is represented by the smallest one in the group, which is very conspicuous in existence on account of its minute size. The X assumes a characteristic tripartite structure showing two constrictions.
The chromosome number in sheep was determined as 54 for diploid and 27 for haploid. After the morphological analysis it was revealed that the diploid complement of the sheep consists of three homologous pairs of atelomitic V-shaped chromosomes, 23 homologous pairs of telomitic rod-shaped ones occurring in a graded series, and an unequal pair of the X and Y which are quite identical in their morphological features to those found in the goat.
Evidence furnished by a close morphological comparison of chromosomes between the goat and the sheep sufficiently indicates that a closely related karyological relationship occurs between these two forms, which is very suggestive of the fact that the ancestral sheep and the ancestral goat probably took their origins from a common ancestor.
