A colony has a female reproductive ant, called a queen, who lays eggs. Those eggs will hatch into worker ants. Larger colonies of ants having millions of ants mostly have female ants making groups of workers, soldiers, or other special castes. Almost all ant colonies also have some fertile male ants called drones.
Rating Newest Oldest. Best Answer: The KâT boundary is a geological signature, usually a thin band, dated to 65.5 million years ago. K is the traditional abbreviation for the Cretaceous period, and T is the abbreviation for the Tertiary period. The boundary marks the end of the Mesozoic era and the beginning of the Cenozoic era, and is associated with the CretaceousâTertiary extinction event, a mass extinction. See the link below for more info. Source(s): http://en.wikipedia.org/wiki/K-t_boundar...
The thymus is the site of T-cell maturation. Thymic epithelial reticular cells attract thymocyte precursors and macrophages. The functional blood-thymus barrier consists of epithelial reticular cells, their basal laminae, and endothelial cells joined by tight junctions. This barrier keeps antigens in blood vessels from entering the thymus, preventing reaction with developing T-cells. The blood-thymus barrier is present in the cortex, but not the medulla. #26 Thymus, 21-month-old