The Role of the Egg Shell and Shell Membranes in Restraining the Entry of Microorganisms

Abstract

ACCORDING to Romanoff and Romanoff (1949) the physical defences of the shell egg against microbial invasion are the shell itself, the shell membranes and the arrangement of the albumen around the yolk. The cross section of the shell is traversed by numerous canals connecting the exterior pores to an interior network of air spaces which lies between the mammillary layer of the shell and the outer shell membrane. This outer membrane is made up of felted fibres lying parallel to the shell. Haines and Moran (1940) indicate that micro passages which exist in this outer membrane are not directly connected to the pore canals. The inner membrane is a three dimensional mesh of very fine keratin and mucin fibres, with the interstices filled with albuminous cementing material.The principal microorganisms which infect shell eggs are gram negative motile rods. The entry of these bacteria is facilitated by the presence of …