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[Embryonal development of grouped lymphoid nodules (Peyer's patches) in the human ileum]
Insights
This study details the prenatal development of Peyer's patches (PP) in the human ileum. Key findings include the timing of PP anlage appearance, growth, and the emergence of lymphocytes and lymphoid nodules during fetal development.
Area of Science:
- Developmental biology
- Immunology
- Human embryology
Background:
- Peyer's patches (PP) are crucial gut-associated lymphoid tissues.
- Understanding PP embryogenesis is vital for comprehending early immune system development.
Purpose of the Study:
- To investigate the embryogenesis and morphological development of human Peyer's patches.
- To track the appearance and maturation of lymphoid cells within Peyer's patches during fetal development.
Main Methods:
- Histological examination of 183 human fetuses aged 8-40 weeks.
- Quantification of Peyer's patch number, size, and superficial area.
- Identification and quantification of lymphocytes (T-cells and B-cells) and lymphoid nodules.
Main Results:
- Peyer's patch anlagen appear by 8-9 weeks gestation, initially in the cranial ileum and spreading caudally.
- Significant increases in PP number and size occur between 15-17 weeks; lymphoid nodules appear by 14 weeks.
- Lymphocytes are present from 8-9 weeks, with increasing T-cell and B-cell percentages throughout gestation, though not reaching adult levels by birth.
Conclusions:
- Human Peyer's patch development is a dynamic process during prenatal life, characterized by distinct stages of formation and cellular differentiation.
- The observed developmental trajectory of Peyer's patches and their cellular components provides a baseline for understanding gut immunity establishment.
Abstract:
Embryogenesis of Payer's patches (PP) of the ileum, has been studied in 183 human fetuses 8-40-week-old. Their anlages appear on the 8th-9th week as an accumulation of atypical villi. At first the PP are localized in the cranial part of the ileum, and then spread caudally. Their most active increase in amount takes place from the 15th up to 17th weeks of development. From the 8th up to the 40th weeks the PP amount increase from 10 up to 37. During the same time their length develops from 0.7 up to 8.3 mm, their width--from 0.3 up to 2.2. The first lymphoid nodules++ in the PP are detected on the 14th week, then their number rises from 200 up to 3,500. The superficial area of all the PP, turning into the lumen of the ileum widens from 1.4 up to 620 mm2. Their predominate form is ellipsoid. During the whole prenatal period in the lymphoid nodules++ no germinative centers are revealed. Lymphocytes in the PP are identified in 8-9-week-old fetuses. By the 29th week the whole amount of lymphocytes in them increase up to 9.6 x 10(6) cells. Lymphocytic suspension of the PP of 8-9-week-old fetuses contains 1.7% of T-lymphocytes (E = POK) and 0.1% of B-lymphocytes (EAC = POK). By the 29th week their amount increases up to 9% and 7%, respectively, but by birth it does not reach their amount in the PP of mature organisms.