Intramammary lymph nodes in cow in early fetal period.

The analysis of serial sections of 4 fetal mammary glands of cattle revealed that the intramammary lymph nodes occurred in these glands. In two cases they were present in both halves of the gland and the number of nodes was 1 to 3 in one half. The nodes were of ovoid shape and their length ranged from 170 to 920 micrometer. The nodes were situated within the mesenchymal primordium of the mammary gland in the neighbourhood of the ramification of the primary epithelial bud into the secondary ones. The microstructure of node was rather primitive. Their capsulae consisted of condensed adjacent mesenchyme and passed over without septa in the supporting nodal reticulum. The lymphoid tissue was not differentiated into the cortex and medulla and consisted of clusters of immature lymphocytes