Abstract
The development of the rat sublingual gland during the first month of postnatal life was analyzed by morphometry. The absolute number of cells in the various morphological glandular compartments - mixed acini with serous demilunes, intercalated ducts, striated ducts and stroma - was determined by the Aherne II morphometric method for particle counting. The data of fresh glandular volume and the number of cells were analyzed by linear, exponential and parabolic regression, with the best fits being obtained with the linear equation. Based on these equations, the growth rate of glandular volume and of each cell population was calculated. Glandular volume increased about 12-fold during the period from 2 to 30 days of postnatal life, corresponding to a rate of 1.34 mm3/day. This volumetric growth of the gland was mainly due to significant 16-, 10-, 4-, 7- and 8-fold increases in the absolute number of mucous acinar, serous demilune, intercalated duct, striated duct and stromal cells, corresponding to a growth rate of 301 x 103, 228 x 103, 19 x 103, 54 x 103 and 247 x 103 cells/day, respectively. Based on the present results, we conclude that the mucous and serous cell populations of the mixed acini grew at a rate close to that of stromal cells, but considerably higher than that obtained for the intercalated duct and striated duct populations, with the lowest growth rate being observed for the ntercalated duct cell population.
Highlights
In contrast to the high degree of immaturity of the rat parotid and submandibular glands at birth, its sublingual glands already consist of the definitive, morphologically still immature, epithelial structures - i.e., mixed acini, intercalated ducts, striated ducts and excretory ducts[15]
We determined the evolution of glandular volume and of the number of cells in each glandular compartment during the first thirty days of postnatal life
Based on the equations that best fitted these data to age in days, the growth rate of glandular volume and of each cell population during this period was calculated
Summary
In contrast to the high degree of immaturity of the rat parotid and submandibular glands at birth, its sublingual glands already consist of the definitive, morphologically still immature, epithelial structures - i.e., mixed acini, intercalated ducts, striated ducts and excretory ducts[15]. The fresh mass of the rat sublingual gland increases by more than 1000% during the first thirty days of postnatal life, and its parenchymatous structures develop morphologically until reaching a pattern similar to that of the adult animal at the end of this period[15,26]. Sublingual gland[24], the growth rate (velocity of growth) of these cell populations during this period of ontogenetic development is still unknown. We determined the evolution of glandular volume and of the number of cells in each glandular compartment during the first thirty days of postnatal life. Based on the equations that best fitted these data to age in days, the growth rate (velocity of growth) of glandular volume and of each cell population during this period was calculated
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