In some organisms, there are special tissues in which chromosomes undergo structural specializations. Such specialized chromosomes are generally termed as SPECIAL TYPES OF CHROMOSOMES.

1. SPECIAL CHROMOSOMES 1
SPECIAL TYPES OF CHROMOSOMES
 The entire eukaryotic organism consists of normal chromosomal set carrying genetic
material in each cell.
 The chromosomal set is specific to particular species level & varies across kingdom.
 In eukaryotes, chromosomes are to standard structure and function of chromosomes as
observed in mitotic or meiotic cells in plants and animals.
 Some eukaryotes besides possessing the usual type of chromosomes contain some
unusual chromosomes.
 These unusual chromosomes are present only in certain special tissues (not seen in other
tissues) and at some particular stage of their life cycle.
 In some organisms, there are special tissues in which chromosomes undergo structural
specializations.
 Such specialized chromosomes are generally termed as SPECIAL TYPES OF
CHROMOSOMES.
 Due to special significance of these chromosomes, a relatively detailed account of these
two types of chromosomes are well accounted.
The special types of eukaryotic chromosomes are classified into following categories:
I. GIANT CHROMOSOMES
These chromosomes are larger in size and are called giant chromosomes.
1. Polytene/Salivary Chromosome
2. Lampbrush Chromosome
II. SUPERNUMERARY CHROMOSOMES
These chromosomes add on to number of normal chromosome and are termed as
Supernumerary Chromosomes.
3. B-Chromosomes
III. Holo-kinetic chromosomes
 The chromosomes of most plants and animals have centromeres that are situated at one
specific position in each chromosome.
 In a number of animals, an especially in insect of the order Hemiptera and a few, mostly
monocotyledonous plants (Juncales, Cyperales), the kinetic activity is distributed over the
entire chromosome and such chromosomes are called Holokinetic chromosomes.