MH 140 Kidney Fetal

Fetal Kidney

This fetal kidney shows the developing lobation of the kidney. Several lobules (#1,#2,#3,#4) are visible in this specimen.

The central lobule will be examined.

• Cortex - darker outer region of each lobule.
  • Renal Corpuscles - consist of Bowman's capsule and a glomerulus.
    • Mature Corpuscles (#1,#2,#3) - in the inner cortex.
    • Developing Corpuscles (#1,#2) - in the outer cortex in various stages of completion.
  • Cortical Labyrinth - region between renal corpuscles and medullary rays.
    • Proximal Convoluted Tubules - their eosinophilic cross-sections are abundant near renal corpuscles. They have a simple cuboidal to columnar epithelium with an irregular, often stellate lumen.
    • Distal Convoluted Tubules - their cross-sections have a simple cuboidal epithelium with a uniform lumen and indistinct boundaries between cells.

• Medullary Rays - projections of tubules in between the cortex and medulla.
  • Proximal Straight Tubules - tubules traveling from the cortex to the medulla with a similar appearance as proximal convoluted tubules.
  • Distal Straight Tubules - tubules traveling from the medulla to the cortex with a similar appearance as distal convoluted tubules.
  • Collecting Ducts - convey urine from nephrons into a minor calyx at the apex of a renal pyramid. Simple cuboidal to columnar epithelium with well-defined boundaries between cells.
• Medulla - lighter inner region of each lobule.
  • Collecting Ducts - large cross-sections with simple cuboidal epithelium and distinct boundaries between cells.
  • Proximal and Distal Straight Tubules - cross-sections with simple cuboidal to columnar epithelium similar to the respective convoluted tubule.
  • Thin Descending and Ascending Limbs (of Henle's Loop) - smaller cross-sections with a simple squamous epithelium.